In U.S. Pat. No. 4,934,086, there is shown a firearm, in particular a pistol, in which a laser sight is mounted in a recoil spring guide chamber. Laser sights are often used by law enforcement authorities in order to enhance the negotiating position of a law enforcement officer when confronting a party subject to arrest. It is reported that once a party subject to arrest recognizes that the party has been targeted with a laser sight, such parties often cease further resistance to arrest and relinquish their own firearms. So, there is a need for a laser sight in such situations.
Certain firearms are not equipped with safety latches. Law enforcement officers are trained to withdraw such a firearm from its holster and place a trigger finger along the recoil spring guide chamber of the firearm. Such technique reduces the cases of inadvertent firing of the firearm. However, it would be desirable to provide the law enforcement officer with a positive reinforcement for this training technique.
There is also a need for a laser sight which may be quickly installed in a pistol without requiring substantial modification of the firearm. Most laser sights for pistols have been accessories that are added by the pistol owner and not by the manufacturer. Such laser sight accessories often require substantial modification of the pistol in order to accommodate the laser sight. In some cases, the modification the extent of the modifications is such that the pistol manufacturer will not further honor the original warranty that was made in connection with the sale of the pistol. Alternatively, lasers can be joined to an exterior of the firearm changing the size, weight and feel of the firearm and requiring use of non-standard holsters. As such, it is desirable to have a laser sight accessory which requires minimal modifications of the pistol so that the original manufacturer warranty is maintained and so that the laser sight can be rapidly installed by the pistol owner or user without requiring installation by a trained technician.
There has also developed a need for a long lasting laser sight. Because current lasers require substantial power, laser sights have been of unduly large size in order to accommodate power supplies needed to maintain the laser in an operating condition for a reasonable amount of time such as 30 minutes. So, the users of laser sights have been faced with the dilemma of shrinking the size of the laser sight but reducing the overall operating life of the battery or having a larger sight that can accommodate a larger battery and thus a longer life. As such, there is a need for a relatively small laser sight with a small power source or battery that lasts for 30 minutes or more.
U.S. Pat. No. 5,509,226 describes one solution to this problem—the spring guide rod laser. This patent describes a laser sight that is disposed substantially entirely within the recoil spring guide chamber of a firearm, such as the recoil cavity of a pistol. As is schematically illustrated in FIGS. 1A and 1B this prior art spring guide rod laser sight 2 has a housing 4 with the following components arranged from back to front—batteries 6 that are electrically connected at one terminal to a battery pin 9 and at another terminal to a high value capacitor 8. A control circuit 10 is electrically connected battery pin 9 by way of capacitor 8. Three leads 11 are carefully soldered to provide a path between control circuit 10 and a laser 12.
Laser 12 generates light when activated by control circuit 10 and this light passes through optics 14 to create a more collimated laser emission. In a spring guide rod laser, housing 4 is sized and shaped based upon a recoil spring guide rod for a firearm and can be substituted for the manufacturer's recoil spring guide rod. A portion of housing 4 proximate lens 14 extends outside of the firearm so that light emitted by laser 12 passes outside of the firearm. Because the spring guide rod is typically co-aligned with an axis of a barrel of a firearm light from the laser is typically placed proximate where a firearm will fire.
A modified take down latch 16 on the firearm is movable from an off position shown in FIG. 1A where a non-conductive portion 18 of a take down latch 16 blocks current from traveling between a battery pin and a conductive path 24 leading to laser 12 and a position where a closed circuit can exist between batteries 6, a battery pin 9, a first conductive surface 14, a second conductive surface 22, a conductive path 24, and laser 12. In FIGS. 1A and 1B conductive path 24 is shown in block form but includes components of the firearm in which spring guide rod laser sight 2 is located such as a recoil chamber of the firearm, and a recoil spring. This introduces potential variability in the electrical path complicating the design of spring guide rod laser sight 2.
The spring guide rod laser allows a laser sight to be incorporated into a pistol without substantially changing the look, feel, or handling of the firearm. While such spring guide rod lasers are technically and commercially successful, it remains desirable to offer new models which can offer advantages such as reducing any or all of the size, complexity and cost of such spring guide rod lasers, reducing manufacturing and product costs, offering more user control over a mode of operation of the spring guide laser, providing improved electrical performance, or improving runtime performance. Of particular interest is making spring guide rod lasers available for use in smaller sized handguns that have relatively small guide rods.
Conventionally, there are many challenges in trying to improve upon the successful design of the prior art spring guide rod lasers. One problem faced is that the small batteries of a size that can be incorporated into a guide rod must also be of a type that is not rapidly self-discharging so that they can be incorporated into the spring guide rod laser and then used weeks, months or even years later. However, such batteries must also be capable of providing sufficient power to allow a laser to generate a laser beam that is visible from a great range when activated. This places a high drain on such batteries requiring significant capacitors that add size and weight to the spring guide rod laser. Additionally, the use of the take down latch and components of the firearm as conductive elements in the system can introduce resistance into the circuit at the points of contact between the spring guide rod laser and the firearm components as well as at points of contact between firearm components that are used to provide such electrical paths. This resistance can add to the burdens placed on the batteries and capacitors.
What are needed in the art are spring guide rod lasers that can overcome such difficulties to enable any of smaller, less expensive, more efficient, longer running, less complex and more feature rich spring guide rod lasers.
Additionally, it has been common for spring guide rod lasers of the prior art to have only one mode of operation—a periodic mode. There have been many reasons for this, one reason for this is that the drive circuit must reliably activate and operate as intended from a powered off state thus introducing mode selection can create unintended issues when start up occurs. Another reason for this is that it is not a trivial matter to provide user access to a mode selector that is to control a circuit that is housed within the central portion of a spring guide rod housing. It also will be understood that it is not a trivial matter to provide a mode selector that will maintain a setting even when exposed to the extreme environment within a firearm spring guide chamber. Further, there are users who will prefer to have the option to change settings without having to access the spring guide rod.
Thus what is also needed in the art is a compact, efficient, reliable, less complex and less expensive spring guide rod laser that can allow a user to select a mode of operation while the spring guide laser is installed in the firearm.